2 Habitat and Niche Habitat Niche All the biotic and abiotic factors in an area where an organism livesNicheAll the physical, chemical, and biological factors needed to surviveHabitat is where an organism livesNiche is how an organism survivesA niche includes food, abiotic conditions, and behavior (reproduction activities)
3 Habitat and Niche Competitive Exclusion Principle Two species competing for the same resourcesOne will be better suited than the otherOne species will be pushed into another nicheThe reason you have this is because of the fact eventually there will be a winner and a loserOne species will somehow have an ever so slight advantage over the other species and will either go extinct or evolve.This is also known as Gause’s law.
4 Habitat and Niche Secondary Outcomes of Competitive Exclusion Niche PartitioningDividing the niche so two species can shareEvolutionary ResponseDivergent evolution could take place to allow two species to survive
5 Habitat and Niche Ecological Equivalants Similar species with similar niches in different geographical regionsSign of convergent evolutionEmerald Tree Boa – South AmericaConvergent evolution – similar species must adapt to environments in different areas – kit fox and red foxGreen Tree Python - Australia
6 Community Interactions Competition – when organisms try to use the same ecological resourcesResources – any necessity of lifeInterspecific CompetitionIntraspecific CompetitionDirect competition will often result in a winner and a loser – eventuallyResources – water, nutrients, light, food, spaceInterspecific – two different species compete for a resource - spaceIntraspcific – members of the same species compete for a resource – water, birds with mates
7 Community Interactions Predation – one organism captures and feeds on anotherPredatorPrey
8 Community Interactions Symbiosis – any relationship where two species live closely togetherThere are different types of symbiosismutualismcommensualismparasitismSymbiotic relationships are essential to any ecosystem
9 Community Interactions Mutualism – both species benefitFlowers and beesClownfish and anemonesTangs and cleaner shrimp
10 Community Interactions Commensalism – one species benefits the other is unharmedSharks and ramorasBarnacles and whales
11 Community Interactions Parasitism – one species benefits and the other is harmedOne organism lives in or on another organism harming it along the wayTapeworms, fleas, ticks, lice
12 Population Density and Distribution Characteristics of PopulationsGeographic distribution – the area inhabited by a populationPopulation density – the number of individuals per unit areaPopulation – a group of individuals of the same species living in the same areaFour main characteristics of a Population – geographic distribution, population density, growth rate, and a population’s age.Geographic distribution can range from a few centimeters to millions of square kilometers.
13 Population Density and Distribution Population DispersionThe amount populations are spread out in relation to one anotherClumpedUniformRandomClumped – live close together in groups-facilitates mating, gains protection, access to food resourcesUniform – territoriality and intraspecies competition leads to this; specific distances from one anotherRandom – Random distribution around an area
14 Population Density and Distribution Survivorship CurvesNumber of individuals surviving over timeType IType IIType III
15 Population Density and Distribution Type ICommon among large mammalsLow infant mortalityGenerally long life
16 Population Density and Distribution Type IIBirds, small mammals, some reptilesConstant threat of death
17 Population Density and Distribution Type IIIInvertebrates, fish, amphibians, plantsHigh infant mortality rate
18 Population Growth Patterns Population Growth – birth rate, death rate, or migrationImmigration – the movement into an areaEmigration - the movement out of a areaPopulations may stay at or near the same amount for some time or they may fluctuate greatly over many years.There are three factors that can affect the population size:1. Births2. Deaths3. Movement into or out of the population.Basically, a population varies based upon the number of individuals added or removed from the population.
19 Population Growth Patterns Exponential Growth – individuals reproduce at a constant rateUnder ideal conditions, a population will grow exponentially.Suppose a bacteria has a doubling time of 20 minutes – 1 will be come 2 in 20 min. etc.In one hour there will be 64 bacteria, in one day there will be 4.7 x 1021 bacteria presentThis is how you get infections that can be extremely serious.If this were graphed out (number vs. time), the graph would look like a JDue to the constant reproduction of individuals, the growth initially is very slow but eventually it will grow infinitely.
21 Population Growth Patterns Logistic Growth – populations growth slows or stops following a period of exponential growthCarrying capacity – the largest number of individuals that the environment can supportPopulation CrashExponential growth would result in the bacteria discussed covering the earth – obviously this hasn’t happened.After a period of exponential growth, the population growth will start to slow due to resources not being as abundant.This leads to an S-shaped curve which signifies logistic growth – exponential growth followed by logistic growth.This is not to say there are not fluctuations in the population – the losses and additions just tend to average out.There will be a point at which the number of individuals within an ecosystem is at a max – carrying capacity.Population crash – a dramatic decline in the population due to a sudden drop in carrying capacity – could be due to a sudden drop in food amounts
22 Population Growth Patterns Limiting Factors – something that causes population growth to decreaseLimiting factors can be food, pressure from predators, availability of shelters.These particular factors can affect the long term survival of a species.
23 Population Growth Patterns Patterns of Population GrowthDemography – the scientific study of human populationsScientists have figured out that the population will not grow forever, but what will limit the growth or keep it in check?There are certain criteria that that scientists look at to determine the growth – birth rates, death rates, age of the population
24 Population Growth Patterns Demographic Transition – a dramatic change in the birth and death ratesU.S., Europe, and JapanChina and IndiaBecause of advances in medicine and health, birth rates are starting to far outweigh the death rates – this leads to rapid increases in populations.Eventually, as societies modernize, increase their education levels, and raise the standard of living then they have less children – this causes the birth rate to fall until it meets the death rate – this is when the demographic transition is complete.
25 Population Growth Patterns Age StructureWhat does it mean if there are lots of older people?What does it mean if there are lots of younger people?Age structure diagramThe graph in the middle suggests that a slow steady growth will occurThe graph on the left suggests that the population may double in the futures
26 Population Growth Patterns Future Population GrowthIs the human population increasing?Will the human population continue to increase forever?What factors will cause the human population to slow?The population is currently growing and may be over 9 billion by 2050
27 Population Growth Patterns Density-dependent factors – limiting factor that depends on population sizeThis may include competition, predation, parasitism, and diseaseThese factors only come into play when the population reaches a certain size.
28 Population Growth Patterns Density-independent factors – factors that affect all populations regardless of sizeWeatherNatural disasterSeasonsHuman activitiesHuman interactions such as hunting, damming rivers and streams, or cutting down forests.
29 Ecological Succession Often times when we view an ecosystem we look at it has always been the way it appearsHowever, every ecosystem is always changing – in response to human intervention, and natural occurences.Not every thing dies at the same time or at the same rate.This is what we call ecological succession - a series of predictable changes in the physical environment
30 Ecological Succession Primary Succession – new species grow where no soil existsThis is the type of succession that occurred after Mt. St. Helens – the land was covered with volcanic ash and lava, there was no dirt.The first species to populate an area under primary succession is called the pioneer species. Often these are lichens – organisms made from fungus and algae that are closely related to bacteria and can perform photosynthesis.As these grow they will break up rock and create soil.
31 Ecological Succession Secondary Succession – a disturbance changes the existing community without removing the soilLand cleared by plowing for farming and then left abandonedAlso occurs when wildfires burn down forrestsSome seeds have even evolved to the point that they will not sprout unless exposed to fire